Pharmacologically, (−)-cis-6-phenyl-5-[4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-5,6,7,8-tetrahydro-naphthalene-2-ol (PPTN) is an estrogen agonist/antagonist that is disclosed in U.S. Pat. No. 5,552,412. An “estrogen agonist/antagonist” is compound that affects some of the same receptors that estrogen does, but not necessarily all, and in some instances, it antagonises or blocks estrogen. It is also known as a “selective estrogen receptor modulator” (SERM). Estrogen agonists/antagonists may also be referred to as antiestrogens although they have some estrogenic activity at some estrogen receptors. Estrogen agonists/antagonists are therefore not what are commonly referred to as “pure antiestrogens”. Antiestrogens that can also act as agonists are referred to as Type I antiestrogens. Type I antiestrogens activate the estrogen receptor to bind tightly in the nucleus for a prolonged time but with impaired receptor replenishment (Clark, et al., Steroids 1973;22:707; Capony, et al., Mol Cell Endocrinol, 1975;3:233).
The compounds of the present invention are metabolites of PPTN and are believed to possess significant pharmacological activities similar or identical to those possessed by the parent compound; PPTN.